Describe the bug

In Python if a cancellation is requested of a workflow with a short-lived activity, and that activity completes during cancellation (unsure if you have to set cancellation type as wait on the activity), the cancellation is effectively swallowed. This occurs for any Python asyncio where cancellation is used, if the awaiting thing swallows cancellation it's like it never happened.

This is probably just existing, unfortunate Python behavior we have to document. We need to at least confirm if it is only for wait-cancel cancellation types or try-cancel too.